A randomized, double-blind, placebo-controlled trial of simvastatin to treat Alzheimer disease

Simvastatin, Its Antimicrobial Activity and Its Prevention of Alzheimer's Disease

Simvastatin, a blockbuster drug for treating hypercholesterolemia, has multifactorial benefits as an antimicrobial agent and plays a preventative role in reducing the incidence of Alzheimer's Disease (AD). Although most of the beneficial effects of simvastatin have been attributed to its ability to reduce cholesterol levels, recent scientific studies have suggested that its benefits are largely due to its pleiotropic effects in targeting other pathways, e.g., by inhibiting protein lipidation. There are certain pleiotropic effects that can be predicted from the inhibition of the mevalonate pathway; however, some of the effects of simvastatin in proteostasis lead to reduced levels of amyloid beta, the key contributor to AD. This review discusses the use of simvastatin as an antimicrobial agent and anti-AD drug.

Unraveling the Connection: Cholesterol, Calcium Signaling, and Neurodegeneration

Cholesterol and calcium play crucial roles as integral structural components and functional signaling entities within the central nervous system. Disruption in cholesterol homeostasis has been linked to Alzheimer's, Parkinson's, and Huntington's Disease while alterations in calcium signaling is hypothesized to be a key substrate for neurodegeneration across many disorders. Despite the importance of regulated cholesterol and calcium homeostasis for brain health there has been an absence of research investigating the interdependence of these signaling molecules and how they can tune each other's abundance at membranes to influence membrane identity. Here, we discuss the role of cholesterol in shaping calcium dynamics in a neurodegenerative disorder that arises due to mutations in the lysosomal cholesterol transporter, Niemann Pick Type C1 (NPC1). We discuss the molecular mechanisms through which altered lysosomal cholesterol transport influences calcium signaling pathways through remodeling of ion channel distribution at organelle-organelle membrane contacts leading to neurodegeneration. This scientific inquiry not only sheds light on NPC disease but also holds implications for comprehending other cholesterol-associated neurodegenerative disorders.

Behavioral and Metabolic Effects of ABCG4 KO in the APPswe,Ind (J9) Mouse Model of Alzheimer's Disease

The pathogenesis of Alzheimer's disease (AD) is complex and involves an imbalance between production and clearance of amyloid-ß peptides (Aß), resulting in accumulation of Aß in senile plaques. Hypercholesterolemia is a major risk factor for developing AD, with cholesterol shown to accumulate in senile plaques and increase production of Aß. ABCG4 is a member of the ATP-binding cassette transporters predominantly expressed in the CNS and has been suggested to play a role in cholesterol and Aß efflux from the brain. In this study, we bred Abcg4 knockout (KO) with the APPSwe,Ind (J9) mouse model of AD to test the hypothesis that loss of Abcg4 would exacerbate the AD phenotype. Unexpectedly, no differences were observed in novel object recognition (NOR) and novel object placement (NOP) behavioral tests, or on histologic examinations of brain tissues for senile plaque numbers. Furthermore, clearance of radiolabeled Aß from the brains did not differ between Abcg4 KO and control mice. Metabolic testing by indirect calorimetry, glucose tolerance test (GTT), and insulin tolerance test (ITT) were also mostly similar between groups with only a few mild metabolic differences noted. Overall, these data suggest that the loss of ABCG4 did not exacerbate the AD phenotype.

Study Partner Type and Adverse Event Reporting in Mild-to-Moderate Alzheimer's Disease Clinical Trials

Background

In randomized clinical trials (RCTs), monitoring adverse events (AEs) and serious AEs (SAEs) is critical. All Alzheimer's disease (AD) RCTs require participants to enroll with a study partner.

Objective

We examined AE reporting rates in mild-to-moderate AD trials and their associations with study partner type.

Methods

We estimated AE reporting rates using placebo data from seven independent RCTs conducted by the Alzheimer's Disease Cooperative Study. We assessed the heterogeneity of reporting rates as a function of visits using generalized estimating equations. In the primary analysis, we tested the hypotheses that the rates of reporting differed by study partner type and time they spent with the participant weekly using Poisson regression with robust variance estimation. In all regression models, log-transformed total patient years was included.

Results

The estimated reporting rates were 2.83 (95% CI: 2.66, 3.02), 1.18 (95% CI: 1.09, 1.28), 0.23 (95% CI: 0.19, 0.27), and 0.28 (95% CI: 0.24, 0.33) events per participant year for grade 1-3 AEs and SAEs, respectively. We estimated that greater number of visits per year was associated with increased reporting for grade 1-2 AEs and SAEs. We did not find evidence to suggest that AE reporting differed by study partner type or by time the study partner spent with the participant.

Conclusions

Study partner type and time the study partner spent with the participant did not appear to impact AE reporting. Estimated reporting rates may be useful to evaluate safety in future studies, particularly those with no control arm and similar visit frequencies.

The Catastrophe of Intracerebral Hemorrhage Drives the Capillary-Hemorrhage Dementias, Including Alzheimer's Disease

This review advances an understanding of several dementias, based on four premises. One is that capillary hemorrhage is prominent in the pathogenesis of the dementias considered (dementia pugilistica, chronic traumatic encephalopathy, traumatic brain damage, Alzheimer's disease). The second premise is that hemorrhage introduces four neurotoxic factors into brain tissue: hypoxia of the tissue that has lost its blood supply, hemoglobin and its breakdown products, excitotoxic levels of glutamate, and opportunistic pathogens that can infect brain cells and induce a cytotoxic immune response. The third premise is that where organisms evolve molecules that are toxic to itself, like the neurotoxicity ascribed to hemoglobin, amyloid- (A), and glutamate, there must be some role for the molecule that gives the organism a selection advantage. The fourth is the known survival-advantage roles of hemoglobin (oxygen transport), of A (neurotrophic, synaptotrophic, detoxification of heme, protective against pathogens) and of glutamate (a major neurotransmitter). From these premises, we propose 1) that the brain has evolved a multi-factor response to intracerebral hemorrhage, which includes the expression of several protective molecules, including haptoglobin, hemopexin and A; and 2) that it is logical, given these premises, to posit that the four neurotoxic factors set out above, which are introduced into the brain by hemorrhage, drive the progression of the capillary-hemorrhage dementias. In this view, A expressed at the loci of neuronal death in these dementias functions not as a toxin but as a first responder, mitigating the toxicity of hemoglobin and the infection of the brain by opportunistic pathogens.

Mechanisms of 3-Hydroxyl 3-Methylglutaryl CoA Reductase in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease worldwide and has a high incidence in the elderly. Unfortunately, there is no effective therapy for AD owing to its complicated pathogenesis. However, the development of lipid-lowering anti-inflammatory drugs has heralded a new era in the treatment of Alzheimer's disease. Several studies in recent years have shown that lipid metabolic dysregulation and neuroinflammation are associated with the pathogenesis of AD. 3-Hydroxyl 3-methylglutaryl CoA reductase (HMGCR) is a rate-limiting enzyme in cholesterol synthesis that plays a key role in cholesterol metabolism. HMGCR inhibitors, known as statins, have changed from being solely lipid-lowering agents to neuroprotective compounds because of their effects on lipid levels and inflammation. In this review, we first summarize the main regulatory mechanism of HMGCR affecting cholesterol biosynthesis. We also discuss the pathogenesis of AD induced by HMGCR, including disordered lipid metabolism, oxidative stress, inflammation, microglial proliferation, and amyloid-β (Aβ) deposition. Subsequently, we explain the possibility of HMGCR as a potential target for AD treatment. Statins-based AD treatment is an ascent field and currently quite controversial; therefore, we also elaborate on the current application prospects and limitations of statins in AD treatment.

Statins and cognitive decline in patients with Alzheimer's and mixed dementia: a longitudinal registry-based cohort study

BACKGROUND

Disturbances in brain cholesterol homeostasis may be involved in the pathogenesis of Alzheimer's disease (AD). Lipid-lowering medications could interfere with neurodegenerative processes in AD through cholesterol metabolism or other mechanisms.

OBJECTIVE

To explore the association between the use of lipid-lowering medications and cognitive decline over time in a cohort of patients with AD or mixed dementia with indication for lipid-lowering treatment.

METHODS

A longitudinal cohort study using the Swedish Registry for Cognitive/Dementia Disorders, linked with other Swedish national registries. Cognitive trajectories evaluated with mini-mental state examination (MMSE) were compared between statin users and non-users, individual statin users, groups of statins and non-statin lipid-lowering medications using mixed-effect regression models with inverse probability of drop out weighting. A dose-response analysis included statin users compared to non-users.

RESULTS

Our cohort consisted of 15,586 patients with mean age of 79.5 years at diagnosis and a majority of women (59.2 %). A dose-response effect was demonstrated: taking one defined daily dose of statins on average was associated with 0.63 more MMSE points after 3 years compared to no use of statins (95% CI: 0.33;0.94). Simvastatin users showed 1.01 more MMSE points (95% CI: 0.06;1.97) after 3 years compared to atorvastatin users. Younger (< 79.5 years at index date) simvastatin users had 0.80 more MMSE points compared to younger atorvastatin users (95% CI: 0.05;1.55) after 3 years. Simvastatin users had 1.03 more MMSE points (95% CI: 0.26;1.80) compared to rosuvastatin users after 3 years. No differences regarding statin lipophilicity were observed. The results of sensitivity analysis restricted to incident users were not consistent.

CONCLUSIONS

Some patients with AD or mixed dementia with indication for lipid-lowering medication may benefit cognitively from statin treatment; however, further research is needed to clarify the findings of sensitivity analyses.

A review on the efficacy and safety of lipid-lowering drugs in neurodegenerative disease

There is a train of thought that lipid therapies may delay or limit the impact of neuronal loss and poor patient outcomes of neurodegenerative diseases (NDDs). A variety of medicines including lipid lowering modifiers (LLMs) are prescribed in NDDs. This paper summarizes the findings of clinical and observational trials including systematic reviews and meta-analyses relating to LLM use in NDDs published in the last 15 years thus providing an up-to-date evidence pool. Three databases were searched PubMed, CINAHL, and Web of Science using key terms relating to the review question. The findings confirm the benefit of LLMs in hyperlipidemic patients with or without cardiovascular risk factors due to their pleotropic effects. In NDDs LLMs are proposed to delay disease onset and slow the rate of progression. Clinical observations show that LLMs protect neurons from α-synuclein, tau, and Aβ toxicity, activation of inflammatory processes, and ultimately oxidative injury. Moreover, current meta-analyses and clinical trials indicated low rates of adverse events with LLMs when used as monotherapy. LLMs appear to have favorable safety and tolerability profiles with few patients stopping treatment due to severe adverse effects. Our collated evidence thus concludes that LLMs have a role in NDDs but further work is needed to understand the exact mechanism of action and reach more robust conclusions on where and when it is appropriate to use LLMs in NDDs in the clinic.

Effects of informant replacement in Alzheimer's disease clinical trials

INTRODUCTION

Alzheimer's disease (AD) trials require enrollment with an informant.

METHODS

We assessed relationships between informant replacement and Alzheimer's Disease Cooperative Study Activities of Daily Living (ADCS-ADL) scores across four AD trials. Using generalized estimating equations, we examined associations between replacement and change in ADCS-ADL between successive visits. We used analysis of covariance to estimate the association between replacement and 18-month change from baseline, and an F-test to compare the variance of this change.

RESULTS

Among 1336 participants, 63 (≈5%) experienced replacement. Between-visit mean change in ADCS-ADL was 2.44 points lower comparing replacement to stable informants (95% confidence interval [CI]: -3.91, -0.98). The difference in between-visit mean absolute change was 2.38 points (95% CI: 1.24, 3.52). Replacement was not significantly associated with an 18-month change from baseline. The ratio of variances (replacement/stable) was 1.80 (95% CI: 1.19, 2.99).

DISCUSSION

Informant replacement is associated with bias and increased variability between visits and increased variance for overall ADCS-ADL.

Alzheimer's Disease: Treatment Today and Tomorrow

Background and Aims

The scope of treatment in Alzheimer's Disease has widened in recent times with FDA approval of new drugs. This review looks at established treatments in AD as well as critically analyses the newer drugs available.

Methods

Data in this review was gathered from PubMed; Google Scholar and MEDLINE from January-March 2023. Search words used were 'Alzheimer's Disease treatment' and 'Dementia treatment'.

Results

Older time tested drugs like Acetyl Choline Receptor Inhibitors and NMDA Receptor antagonists remain the mainstay of pharmacological treatment in AD. Despite a lot of excitement about newer FDA approved drugs; we have to be cautious in their use. Aducanumab showed good reduction in CSF amyloid levels (biomarker of AD); but this did not necessarily translate into better clinical outcomes of patients.

Conclusion

Despite the recent advances and approval of drugs in treatment of AD, we have to exhibit caution while prescribing these drugs. Even with a sound mechanism of action, these drugs do not always show improvement in clinical outcomes. More clinical trials are required for development of drugs in treatment of AD which explore various different mechanisms of action.

Behavioral and metabolic and effects of ABCG4 KO in the APPswe,Ind (J9) mouse model of Alzheimer's disease

The pathogenesis of Alzheimer's disease (AD) is complex and involves an imbalance between production and clearance of amyloid-ß peptides (Aß), resulting in accumulation of Aß in senile plaques. Hypercholesterolemia is a major risk factor for developing AD, with cholesterol shown to accumulate in senile plaques and increase production of Aß. ABCG4 is a member of the ATP-binding cassette transporters predominantly expressed in the CNS, and has been suggested to play a role in cholesterol and Aß efflux from the brain. In this study, we bred Abcg4 knockout (KO) with the APPSwe,Ind (J9) mouse model of AD to test the hypothesis that loss of Abcg4 would exacerbate the AD phenotype. Unexpectedly, no differences were observed in Novel object recognition (NOR) and Novel object placement (NOP) behavioral tests, or on histologic examinations of brain tissues for senile plaque numbers. Furthermore, clearance of radiolabeled Aß from the brains did not differ between Abcg4 KO and control mice. Metabolic testing by indirect calorimetry, glucose tolerance test (GTT) and insulin tolerance test (ITT), were also mostly similar between groups with only a few mild metabolic differences noted. Overall these data suggest that the loss of ABCG4 did not exacerbate the AD phenotype.

Acute ACAT1/SOAT1 Blockade Increases MAM Cholesterol and Strengthens ER-Mitochondria Connectivity

Cholesterol is a key component of all mammalian cell membranes. Disruptions in cholesterol metabolism have been observed in the context of various diseases, including neurodegenerative disorders such as Alzheimer's disease (AD). The genetic and pharmacological blockade of acyl-CoA:cholesterol acyltransferase 1/sterol O-acyltransferase 1 (ACAT1/SOAT1), a cholesterol storage enzyme found on the endoplasmic reticulum (ER) and enriched at the mitochondria-associated ER membrane (MAM), has been shown to reduce amyloid pathology and rescue cognitive deficits in mouse models of AD. Additionally, blocking ACAT1/SOAT1 activity stimulates autophagy and lysosomal biogenesis; however, the exact molecular connection between the ACAT1/SOAT1 blockade and these observed benefits remain unknown. Here, using biochemical fractionation techniques, we observe cholesterol accumulation at the MAM which leads to ACAT1/SOAT1 enrichment in this domain. MAM proteomics data suggests that ACAT1/SOAT1 inhibition strengthens the ER-mitochondria connection. Confocal and electron microscopy confirms that ACAT1/SOAT1 inhibition increases the number of ER-mitochondria contact sites and strengthens this connection by shortening the distance between these two organelles. This work demonstrates how directly manipulating local cholesterol levels at the MAM can alter inter-organellar contact sites and suggests that cholesterol buildup at the MAM is the impetus behind the therapeutic benefits of ACAT1/SOAT1 inhibition.

Lipid metabolism and Alzheimer's disease: clinical evidence, mechanistic link and therapeutic promise

Alzheimer's disease (AD) is an age-associated neurodegenerative disorder with multifactorial etiology, intersecting genetic and environmental risk factors, and a lack of disease-modifying therapeutics. While the abnormal accumulation of lipids was described in the very first report of AD neuropathology, it was not until recent decades that lipid dyshomeostasis became a focus of AD research. Clinically, lipidomic and metabolomic studies have consistently shown alterations in the levels of various lipid classes emerging in early stages of AD brains. Mechanistically, decades of discovery research have revealed multifaceted interactions between lipid metabolism and key AD pathogenic mechanisms including amyloidogenesis, bioenergetic deficit, oxidative stress, neuroinflammation, and myelin degeneration. In the present review, converging evidence defining lipid dyshomeostasis in AD is summarized, followed by discussions on mechanisms by which lipid metabolism contributes to pathogenesis and modifies disease risk. Furthermore, lipid-targeting therapeutic strategies, and the modification of their efficacy by disease stage, ApoE status, and metabolic and vascular profiles, are reviewed.

Metabolic Syndrome as a Risk Factor for Alzheimer's Disease: A Focus on Insulin Resistance

Alzheimer's disease (AD) is the main type of dementia and is a disease with a profound socioeconomic burden due to the lack of effective treatment. In addition to genetics and environmental factors, AD is highly associated with metabolic syndrome, defined as the combination of hypertension, hyperlipidemia, obesity and type 2 diabetes mellitus (T2DM). Among these risk factors, the connection between AD and T2DM has been deeply studied. It has been suggested that the mechanism linking both conditions is insulin resistance. Insulin is an important hormone that regulates not only peripheral energy homeostasis but also brain functions, such as cognition. Insulin desensitization, therefore, could impact normal brain function increasing the risk of developing neurodegenerative disorders in later life. Paradoxically, it has been demonstrated that decreased neuronal insulin signalling can also have a protective role in aging and protein-aggregation-associated diseases, as is the case in AD. This controversy is fed by studies focused on neuronal insulin signalling. However, the role of insulin action on other brain cell types, such as astrocytes, is still unexplored. Therefore, it is worthwhile exploring the involvement of the astrocytic insulin receptor in cognition, as well as in the onset and/or development of AD.

Recruitment across two decades of NIH-funded Alzheimer's disease clinical trials

BACKGROUND

Timely accrual of a representative sample is a key factor in whether Alzheimer's disease (AD) clinical trials successfully answer the scientific questions under study. Studies in other fields have observed that, over time, recruitment to trials has become increasingly reliant on larger numbers of sites, with declines in the average per-site recruitment rate. Here, we examined the trends in recruitment over a 20-year period of NIH-funded AD clinical trials conducted by the Alzheimer's Disease Cooperative Study (ADCS), a temporally consistent network of sites devoted to interventional research.

METHODS

We performed retrospective analyses of eleven ADCS randomized clinical trials. To examine the recruitment planning, we calculated the expected number of participants to be enrolled per site for each trial. To examine the actual trial recruitment rates, we quantified the number of participants enrolled per site per month.

RESULTS

No effects of time were observed on recruitment planning or overall recruitment rates across trials. No trial achieved an overall recruitment rate greater than one subject per site per month. We observed the fastest recruitment rates in trials with no competition and the slowest in trials that overlapped in time. The highest recruitment rates were consistently seen early within trials and declined over the course of studies.

CONCLUSIONS

Trial recruitment projections should plan for fewer than one participant randomized per site per month and consider the number of other AD trials being conducted concurrently.

The Spectrum of Alzheimer-Type Pathology in Cognitively Normal Individuals

BACKGROUND

The strongest risk factor for the development of Alzheimer's disease (AD) is age. The progression of Braak stage and Thal phase with age has been demonstrated. However, prior studies did not include cognitive status.

OBJECTIVE

We set out to define normative values for Alzheimer-type pathologic changes in individuals without cognitive decline, and then define levels that would qualify them to be resistant to or resilient against these changes.

METHODS

Utilizing neuropathology data obtained from the National Alzheimer's Coordinating Center (NACC), we demonstrate the age-related progression of Alzheimer-type pathologic changes in cognitively normal individuals (CDR = 0, n = 542). With plots generated from these data, we establish standard lines that may be utilized to measure the extent to which an individual's Alzheimer-type pathology varies from the estimated normal range of pathology.

RESULTS

Although Braak stage and Thal phase progressively increase with age in cognitively normal individuals, the Consortium to Establish a Registry for Alzheimer's Disease neuritic plaque score and Alzheimer's disease neuropathologic change remain at low levels.

CONCLUSION

These findings suggest that an increasing burden of neuritic plaques is a strong predictor of cognitive decline, whereas, neurofibrillary degeneration and amyloid-β (diffuse) plaque deposition, both to some degree, are normal pathologic changes of aging that occur in almost all individuals regardless of cognitive status. Furthermore, we have defined the amount of neuropathologic change in cognitively normal individuals that would qualify them to be "resilient" against the pathology (significantly above the normative values for age, but still cognitively normal) or "resistant" to the development of pathology (significantly below the normative values for age).

Cardiovascular Risk Factors and Risk of Alzheimer Disease and Mortality: A Latent Class Approach

Background Cardiovascular risk factors co-occur with one another, and little is known about the extent of their clustering and risk of Alzheimer disease (AD). We identify groups of cardiovascular risk factors in cognitively normal individuals and investigate between-group differences in incident AD and death. Methods and Results Cognitively normal individuals were recruited from the National Alzheimer's Coordinator Center. A latent class analysis was conducted with hypertension, hypercholesterolemia, heart condition, stroke, smoking history, diabetes, and high body mass index. Between-group differences in the incidence of AD, mortality, and mortality-adjusted AD were investigated. This study included 12 412 cognitively normal individuals (average follow-up, 65 months). Three groups were identified: (1) low probabilities of cardiovascular risk factors (reference; N=5398 [43%]), (2) hypertension and hypercholesterolemia (vascular-dominant; N=5721 [46%]), and (3) hypertension, hypercholesterolemia, diabetes, and high body mass index (vascular-metabolic; N=1293 [10%]). Both vascular groups were significantly older, had more men, were slightly less educated, and were slightly more cognitively impaired than the reference group (all P<0.05). However, only the vascular-metabolic group had a significantly younger age of death compared with the reference group (84.3 versus 88.7 years, P<0.001). Only the vascular-dominant group had a greater incidence of AD (odds ratio [OR], 1.30; P<0.001) compared with the reference group. Mortality was greater in the vascular-dominant (OR, 3.26; P<0.001) and vascular-metabolic groups (OR, 1.84; P=0.02). Mortality-adjusted AD was greater in the vascular-dominant (OR, 1.54; P=0.02) and vascular-metabolic groups (OR, 1.46; P=0.04). Conclusions Three distinct cardiovascular risk factor groups were identified in cognitively normal elderly individuals. Only the vascular-dominant group was associated with a greater incidence of AD. Selective mortality may contribute to the attenuated association between the vascular-metabolic group and incident AD.

Incorporating historical control information in ANCOVA models using the meta-analytic-predictive approach

The meta-analytic-predictive (MAP) approach is a Bayesian meta-analytic method to synthesize and incorporate information from historical controls in the analysis of a new trial. Classically, only a single parameter, typically the intercept or rate, is assumed to vary across studies, which may not be realistic in more complex models. Analysis of covariance (ANCOVA) is often used to analyze trials with a pretest-posttest design, where both the intercept and the baseline effect (coefficient of the outcome at baseline) affect the estimated treatment effect. We extended the MAP approach to ANCOVA, to allow for variation in the intercept and the baseline effect across studies, and possibly also correlation between these parameters. The method was illustrated using data from the Alzheimer's Disease Cooperative Study (ADCS) and assessed with a simulation study. In the ADCS data, the proposed multivariate MAP approach yielded a prior effective sample size of 79 and 58 for the intercept and the baseline effect respectively and reduced the posterior standard deviation of the treatment effect by 12.6%. The result was robust to the choice of prior for the between-study variation. In the simulations, the proposed approach yielded power gains with a good control of the type I error rate. Ignoring the between-study correlation of the parameters or assuming no variation in the baseline effect generally led to less power gain. In conclusion, the MAP approach can be extended to a multivariate version for ANCOVA, which may improve the estimation of the treatment effect.

Therapeutic drug repositioning with special emphasis on neurodegenerative diseases: Threats and issues

Drug repositioning or repurposing is the process of discovering leading-edge indications for authorized or declined/abandoned molecules for use in different diseases. This approach revitalizes the traditional drug discovery method by revealing new therapeutic applications for existing drugs. There are numerous studies available that highlight the triumph of several drugs as repurposed therapeutics. For example, sildenafil to aspirin, thalidomide to adalimumab, and so on. Millions of people worldwide are affected by neurodegenerative diseases. According to a 2021 report, the Alzheimer's disease Association estimates that 6.2 million Americans are detected with Alzheimer's disease. By 2030, approximately 1.2 million people in the United States possibly acquire Parkinson's disease. Drugs that act on a single molecular target benefit people suffering from neurodegenerative diseases. Current pharmacological approaches, on the other hand, are constrained in their capacity to unquestionably alter the course of the disease and provide patients with inadequate and momentary benefits. Drug repositioning-based approaches appear to be very pertinent, expense- and time-reducing strategies for the enhancement of medicinal opportunities for such diseases in the current era. Kinase inhibitors, for example, which were developed for various oncology indications, demonstrated significant neuroprotective effects in neurodegenerative diseases. This review expounds on the classical and recent examples of drug repositioning at various stages of drug development, with a special focus on neurodegenerative disorders and the aspects of threats and issues viz. the regulatory, scientific, and economic aspects.

Statins Use in Alzheimer Disease: Bane or Boon from Frantic Search and Narrative Review

Alzheimer’s disease (AD) was used to describe pre-senile dementia to differentiate it from senile dementia, which develops in the adult age group of more than 65 years. AD is characterized by the deposition of amyloid beta (Aβ) plaque and tau-neurofibrillary tangles (TNTs) in the brain. The neuropathological changes in AD are related to the deposition of amyloid plaques, neurofibrillary tangles, and progression of neuroinflammation, neuronal mitochondrial dysfunction, autophagy dysfunction, and cholinergic synaptic dysfunction. Statins are one of the main cornerstone drugs for the management of cardiovascular disorders regardless of dyslipidemia status. Increasing the use of statins, mainly in the elderly groups for primary and secondary prevention of cardiovascular diseases, may affect their cognitive functions. Extensive and prolonged use of statins may affect cognitive functions in healthy subjects and dementia patients. Statins-induced cognitive impairments in both patients and health providers had been reported according to the post-marketing survey. This survey depends mainly on sporadic cases, and no cognitive measures were used. Evidence from prospective and observational studies gives no robust conclusion regarding the beneficial or detrimental effects of statins on cognitive functions in AD patients. Therefore, this study is a narrative review aimed with evidences to the beneficial, detrimental, and neutral effects of statins on AD.

Medication-Wide Association Study Plus (MWAS+): A Proof of Concept Study on Drug Repurposing

The high cost and time for developing a new drug or repositioning a partially-developed drug has fueled interest in “repurposing” drugs. Drug repurposing is particularly of interest for Alzheimer’s disease (AD) or AD-related dementias (ADRD) because there are no unrestricted disease-modifying treatments for ADRD. We have designed and pilot tested a 3-Step Medication-Wide Association Study Plus (MWAS+) approach to rigorously accelerate the identification of drugs with a high potential to be repurposed for delaying and preventing AD/ADRD: Step 1 is a hypothesis-free exploration; Step 2 is mechanistic filtering; And Step 3 is hypothesis testing using observational data and prospective cohort design. Our results demonstrated the feasibility of the MWAS+ approach. The Step 1 analysis identified potential candidate drugs including atorvastatin and GLP1. The literature search in Step 2 found evidence supporting the mechanistic plausibility of the statin-ADRD association. Finally, Step 3 confirmed our hypothesis that statin may lower the risk of incident ADRD, which was statistically significant using a target trial design that emulated randomized controlled trials.

The Dose and Duration-dependent Association between Melatonin Treatment and Overall Cognition in Alzheimer's Dementia: A Network Meta- Analysis of Randomized Placebo-Controlled Trials

BACKGROUND

While Alzheimer's dementia (AD) has a prevalence as high as 3-32% and is associated with cognitive dysfunction and the risk of institutionalization, no efficacious and acceptable treatments can modify the course of cognitive decline in AD. Potential benefits of exogenous melatonin for cognition have been divergent across trials.

OBJECTIVE

The current network meta-analysis (NMA) was conducted under the frequentist model to evaluate the potential beneficial effects of exogenous melatonin supplementation on overall cognitive function in participants with AD in comparison to other FDA-approved medications (donepezil, galantamine, rivastigmine, memantine, and Namzaric).

METHODS

The primary outcome was the changes in the cognitive function [measured by mini-mental state examination (MMSE)] after treatment in patients with Alzheimer's dementia. The secondary outcomes were changes in the quality of life, behavioral disturbance, and acceptability (i.e., drop-out due to any reason and rate of any adverse event reported).

RESULTS

The current NMA of 50 randomized placebo-controlled trials (RCTs) revealed the medium-term lowdose melatonin to be associated with the highest post-treatment MMSE (mean difference = 1.48 in MMSE score, 95% confidence intervals [95% CIs] = 0.51 to 2.46) and quality of life (standardized mean difference = -0.64, 95% CIs = -1.13 to -0.15) among all of the investigated medications in the participants with AD. Finally, all of the investigated exogenous melatonin supplements were associated with similar acceptability as was the placebo.

CONCLUSION

The current NMA provides evidence for the potential benefits of exogenous melatonin supplementation, especially medium-term low-dose melatonin, in participants with AD.

Immune Response at the Crossroads of Atherosclerosis and Alzheimer's Disease

Alzheimer's disease (AD) and cardiovascular disease (CVD) are pathologies that are characterized by common signatures of vascular dysfunction and chronic inflammation that are accelerated with aging. Importantly, epidemiological studies report an independent interaction between AD and CVD and data suggest that chronic inflammation in CVD may accelerate AD development. Atherosclerosis affects most large to medium sized arteries including those supplying the cerebral circulation. Vascular dysfunction caused by atherosclerosis results in blood brain barrier breakdown, inflammation, an impaired clearance of amyloid-beta (Aβ), and finally ends with neurovascular dysfunction. Numerous data indicate that innate and adaptive immune responses shape atherogenesis and increasing evidence suggests an implication of the immune response in AD progression. Currently, mechanisms by which these two diseases are interconnected with each other are not well-defined. In this review, we discuss the recent advances in our understanding of the intertwined role of the immune response in atherosclerosis and AD and the implications of these findings for human health.

Advances in PPARs Molecular Dynamics and Glitazones as a Repurposing Therapeutic Strategy through Mitochondrial Redox Dynamics against Neurodegeneration

Peroxisome proliferator-activated receptors (PPARs) activity has significant implications for the development of novel therapeutic modalities against neurodegenerative diseases. Although PPAR-α, PPAR-β/δ, and PPAR-γ nuclear receptor expressions are significantly reported in the brain, their implications in brain physiology and other neurodegenerative diseases still require extensive studies. PPAR signaling can modulate various cell signaling mechanisms involved in the cells contributing to on- and off-target actions selectively to promote therapeutic effects as well as the adverse effects of PPAR ligands. Both natural and synthetic ligands for the PPARα, PPARγ, and PPARβ/δ have been reported. PPARα (WY 14.643) and PPARγ agonists can confer neuroprotection by modulating mitochondrial dynamics through the redox system. The pharmacological effect of these agonists may deliver effective clinical responses by protecting vulnerable neurons from Aβ toxicity in Alzheimer's disease (AD) patients. Therefore, the current review delineated the ligands' interaction with 3D-PPARs to modulate neuroprotection, and also deciphered the efficacy of numerous drugs, viz. Aβ aggregation inhibitors, vaccines, and γ-secretase inhibitors against AD; this review elucidated the role of PPAR and their receptor isoforms in neural systems, and neurodegeneration in human beings. Further, we have substantially discussed the efficacy of PPREs as potent transcription factors in the brain, and the role of PPAR agonists in neurotransmission, PPAR gamma coactivator-1α (PGC-1α) and mitochondrial dynamics in neuroprotection during AD conditions. This review concludes with the statement that the development of novel PPARs agonists may benefit patients with neurodegeneration, mainly AD patients, which may help mitigate the pathophysiology of dementia, subsequently improving overall the patient's quality of life.

Alzheimer's Disease: Key Insights from Two Decades of Clinical Trial Failures

Given the acknowledged lack of success in Alzheimer’s disease (AD) drug development over the past two decades, the objective of this review was to derive key insights from the myriad failures to inform future drug development. A systematic and exhaustive review was performed on all failed AD compounds for dementia (interventional phase II and III clinical trials from ClinicalTrials.gov) from 2004 to the present. Starting with the initial ∼2,700 AD clinical trials, ∼550 trials met our initial criteria, from which 98 unique phase II and III compounds with various mechanisms of action met our criteria of a failed compound. The two recent reported phase III successes of aducanumab and oligomannate are very encouraging; however, we are awaiting real-world validation of their effectiveness. These two successes against the 98 failures gives a 2.0% phase II and III success rate since 2003, when the previous novel compound was approved. Potential contributing methodological factors for the clinical trial failures were categorized into 1) insufficient evidence to initiate the pivotal trials, and 2) pivotal trial design shortcomings. Our evaluation found that rational drug development principles were not always followed for AD therapeutics development, and the question remains whether some of the failed compounds may have shown efficacy if the principles were better adhered to. Several recommendations are made for future AD therapeutic development. The whole database of the 98 failed compounds is presented in the Supplementary Material.

The role of DHCR24 in the pathogenesis of AD: re-cognition of the relationship between cholesterol and AD pathogenesis

Previous studies show that 3β-hydroxysterol-Δ24 reductase (DHCR24) has a remarked decline in the brain of AD patients. In brain cholesterol synthetic metabolism, DHCR24 is known as the heavily key synthetase in cholesterol synthesis. Moreover, mutations of DHCR24 gene result in inhibition of the enzymatic activity of DHCR24, causing brain cholesterol deficiency and desmosterol accumulation. Furthermore, in vitro studies also demonstrated that DHCR24 knockdown lead to the inhibition of cholesterol synthesis, and the decrease of plasma membrane cholesterol and intracellular cholesterol level. Obviously, DHCR24 could play a crucial role in maintaining cholesterol homeostasis via the control of cholesterol synthesis. Over the past two decades, accumulating data suggests that DHCR24 activity is downregulated by major risk factors for AD, suggesting a potential link between DHCR24 downregulation and AD pathogenesis. Thus, the brain cholesterol loss seems to be induced by the major risk factors for AD, suggesting a possible causative link between brain cholesterol loss and AD. According to previous data and our study, we further found that the reduced cholesterol level in plasma membrane and intracellular compartments by the deficiency of DHCR24 activity obviously was involved in β-amyloid generation, tau hyperphosphorylation, apoptosis. Importantly, increasing evidences reveal that the brain cholesterol loss and lipid raft disorganization are obviously linked to neuropathological impairments which are associated with AD pathogenesis. Therefore, based on previous data and research on DHCR24, we suppose that the brain cholesterol deficiency/loss might be involved in the pathogenesis of AD.

Pharmacogenetic Analyses of Therapeutic Effects of Lipophilic Statins on Cognitive and Functional Changes in Alzheimer’s Disease

Background: Pharmacogenetic effects of statins on clinical changes in Alzheimer’s disease (AD) could be mediated by epistatic interactions among relevant genetic variants involved in cholesterol metabolism. Objective: To investigate associations of HMGCR (rs3846662), NR1H2 (rs2695121), or CETP (rs5882&rs708272) with cognitive and functional changes in AD, with stratification according to APOE ɛ4 carrier status and lipid-lowering treatment with lipophilic statins. Methods: Consecutive outpatients with late-onset AD were screened with cognitive tests, while caregivers scored functionality and global ratings, with prospective neurotranslational associations documented for one year. Results: Considering n = 190:142 had hypercholesterolemia, 139 used lipophilic statins; minor allele frequencies were 0.379 (rs2695121-T:46.3% heterozygotes), 0.368 (rs5882-G:49.5% heterozygotes), and 0.371 (rs708272-A:53.2% heterozygotes), all in Hardy-Weinberg equilibrium. For APOE ɛ4 carriers: rs5882-GG protected from cognitive decline; rs5882-AA caused faster cognitive decline; carriers of rs2695121-CC or rs5882-AA were more susceptible to harmful cognitive effects of lipophilic statins; carriers of rs5882-GG or rs708272-AG had functional benefits when using lipophilic statins. APOE ɛ4 non-carriers resisted any cognitive or functional effects of lipophilic statins, while invariability of rs3846662 (all AA) prevented the assessment of HMGCR effects. When assessing CETP haplotypes only: rs5882-GG protected from cognitive and functional decline, regardless of lipophilic statin therapy; lipophilic statins usually caused cognitive and functional harm to carriers of rs5882-A and/or rs708272-A; lipophilic statins benefitted cognition and functionality of carriers of rs5882-G and/or rs708272-G. Conclusion: Reportedly protective variants of CETP and NR1H2 also slowed cognitive and functional decline particularly for APOE ɛ4 carriers, and regardless of cholesterol variations, while therapy with lipophilic statins might affect carriers of specific genetic variants.

Vascular Cognitive Impairment (VCI)

Vascular cognitive impairment (VCI) is predominately caused by vascular risk factors and cerebrovascular disease. VCI includes a broad spectrum of cognitive disorders, from mild cognitive impairment to vascular dementia caused by ischemic or hemorrhagic stroke, and vascular factors alone or in a combination with neurodegeneration including Alzheimer's disease (AD) and AD-related dementia. VCI accounts for at least 20-40% of all dementia diagnosis. Growing evidence indicates that cerebrovascular pathology is the most important contributor to dementia, with additive or synergistic interactions with neurodegenerative pathology. The most common underlying mechanism of VCI is chronic age-related dysregulation of CBF, although other factors such as inflammation and cardiovascular dysfunction play a role. Vascular risk factors are prevalent in VCI and if measured in midlife they predict cognitive impairment and dementia in later life. Particularly, hypertension, high cholesterol, diabetes, and smoking at midlife are each associated with a 20 to 40% increased risk of dementia. Control of these risk factors including multimodality strategies with an inclusion of lifestyle modification is the most promising strategy for treatment and prevention of VCI. In this review, we present recent developments in age-related VCI, its mechanisms, diagnostic criteria, neuroimaging correlates, vascular risk determinants, and current intervention strategies for prevention and treatment of VCI. We have also summarized the most recent and relevant literature in the field of VCI.

Impact of potential modifications to Alzheimer's disease clinical trials in response to disruption by COVID-19: a simulation study

BACKGROUND

The COVID-19 pandemic disrupted Alzheimer disease randomized clinical trials (RCTs), forcing investigators to make changes in the conduct of such trials while endeavoring to maintain their validity. Changing ongoing RCTs carries risks for biases and threats to validity. To understand the impact of exigent modifications due to COVID-19, we examined several scenarios in symptomatic and disease modification trials that could be made.

METHODS

We identified both symptomatic and disease modification Alzheimer disease RCTs as exemplars of those that would be affected by the pandemic and considered the types of changes that sponsors could make to each. We modeled three scenarios for each of the types of trials using existing datasets, adjusting enrollment, follow-ups, and dropouts to examine the potential effects COVID-19-related changes. Simulations were performed that accounted for completion and dropout patterns using linear mixed effects models, modeling time as continuous and categorical. The statistical power of the scenarios was determined.

RESULTS

Truncating both symptomatic and disease modification trials led to underpowered trials. By contrast, adapting the trials by extending the treatment period, temporarily stopping treatment, delaying outcomes assessments, and performing remote assessment allowed for increased statistical power nearly to the level originally planned.

DISCUSSION

These analyses support the idea that disrupted trials under common scenarios are better continued and extended even in the face of dropouts, treatment disruptions, missing outcomes, and other exigencies and that adaptations can be made that maintain the trials' validity. We suggest some adaptive methods to do this noting that some changes become under-powered to detect the original effect sizes and expected outcomes. These analyses provide insight to better plan trials that are resilient to unexpected changes to the medical, social, and political milieu.

An evidence-based review of neuronal cholesterol role in dementia and statins as a pharmacotherapy in reducing risk of dementia

INTRODUCTION

Dementia is a progressive neurodegenerative disorder impairing memory and cognition. Alzheimer's Disease, followed by vascular dementia - the most typical form. Risk factors for vascular dementia include diabetes, cardiovascular disease, hyperlipidemia. Lipids' levels are significantly associated with vascular changes in the brain.

AREAS COVERED

The present article reviews the cholesterol metabolism in the brain, which includes: the synthesis, transport, storage, and elimination process. Additionally, it reviews the role of cholesterol in the pathogenesis of dementia and statin as a therapeutic intervention in dementia. In addition to the above, it further reviews evidence in support of as well as against statin therapy in dementia, recent updates of statin pharmacology, and demerits of use of statin pharmacotherapy.

EXPERT OPINION

Amyloid-β peptides and intraneuronal neurofibrillary tangles are markers of Alzheimer's disease. Evidence shows cholesterol modulates the functioning of enzymes associated with Amyloid-β peptide processing and synthesis. Lowering cholesterol using statin may help prevent or delay the progression of dementia. This paper reviews the role of statin in dementia and recommends extensive future studies, including genetic research, to obtain a precise medication approach for patients with dementia.

Lipids in Pathophysiology and Development of the Membrane Lipid Therapy: New Bioactive Lipids

Membranes are mainly composed of a lipid bilayer and proteins, constituting a checkpoint for the entry and passage of signals and other molecules. Their composition can be modulated by diet, pathophysiological processes, and nutritional/pharmaceutical interventions. In addition to their use as an energy source, lipids have important structural and functional roles, e.g., fatty acyl moieties in phospholipids have distinct impacts on human health depending on their saturation, carbon length, and isometry. These and other membrane lipids have quite specific effects on the lipid bilayer structure, which regulates the interaction with signaling proteins. Alterations to lipids have been associated with important diseases, and, consequently, normalization of these alterations or regulatory interventions that control membrane lipid composition have therapeutic potential. This approach, termed membrane lipid therapy or membrane lipid replacement, has emerged as a novel technology platform for nutraceutical interventions and drug discovery. Several clinical trials and therapeutic products have validated this technology based on the understanding of membrane structure and function. The present review analyzes the molecular basis of this innovative approach, describing how membrane lipid composition and structure affects protein-lipid interactions, cell signaling, disease, and therapy (e.g., fatigue and cardiovascular, neurodegenerative, tumor, infectious diseases).

Metabolic Syndrome and Cognitive Function

PURPOSE OF REVIEW

Metabolic syndrome (MetS) is a cluster of cardiovascular disease risk factors that are related to several adverse health outcomes, including poor cognitive function. This review seeks to summarize and critically review select recent findings on the association between MetS and cognition.

RECENT FINDINGS

MetS was associated with lower domain-specific and global cognitive function in most cross-sectional studies, but findings from longitudinal studies are not consistent. The associations varied depending on age, sex, cognitive test, genetic susceptibility, and the duration of follow-up in prospective studies. MetS was associated with a higher risk of mild cognitive impairment (MCI) and progression from MCI to dementia, particularly vascular dementia. Among MetS components, high blood pressure, high waist circumference, and hyperglycemia were the strongest predictors of cognitive function. MetS is associated with higher risk of cognitive impairment. Research is needed on how preventing or treating MetS affects cognition.

A multitude of signaling pathways associated with Alzheimer's disease and their roles in AD pathogenesis and therapy

The exact molecular mechanisms associated with Alzheimer's disease (AD) pathology continue to represent a mystery. In the past decades, comprehensive data were generated on the involvement of different signaling pathways in the AD pathogenesis. However, the utilization of signaling pathways as potential targets for the development of drugs against AD is rather limited due to the immense complexity of the brain and intricate molecular links between these pathways. Therefore, finding a correlation and cross-talk between these signaling pathways and establishing different therapeutic targets within and between those pathways are needed for better understanding of the biological events responsible for the AD-related neurodegeneration. For example, autophagy is a conservative cellular process that shows link with many other AD-related pathways and is crucial for maintenance of the correct cellular balance by degrading AD-associated pathogenic proteins. Considering the central role of autophagy in AD and its interplay with many other pathways, the finest therapeutic strategy to fight against AD is the use of autophagy as a target. As an essential step in this direction, this comprehensive review represents recent findings on the individual AD-related signaling pathways, describes key features of these pathways and their cross-talk with autophagy, represents current drug development, and introduces some of the multitarget beneficial approaches and strategies for the therapeutic intervention of AD.

Role of cholesterol in substrate recognition by [Formula: see text]-secretase

[Formula: see text]-Secretase is an enzyme known to cleave multiple substrates within their transmembrane domains, with the amyloid precursor protein of Alzheimer's Disease among the most prominent examples. The activity of [Formula: see text]-secretase strictly depends on the membrane cholesterol content, yet the mechanistic role of cholesterol in the substrate binding and cleavage remains unclear. In this work, we used all-atom molecular dynamics simulations to examine the role of cholesterol in the initial binding of a direct precursor of [Formula: see text]-amyloid polypeptides by [Formula: see text]-secretase. We showed that in cholesterol-rich membranes, both the substrate and the enzyme region proximal to the active site induce a local membrane thinning. With the free energy methods we found that in the presence of cholesterol the substrate binds favorably to the identified exosite, while cholesterol depletion completely abolishes the binding. To explain these findings, we directly examined the role of hydrophobic mismatch in the substrate binding to [Formula: see text]-secretase, showing that increased membrane thickness results in higher propensity of the enzyme to bind substrates. Therefore, we propose that cholesterol promotes substrate binding to [Formula: see text]-secretase by increasing the membrane thickness, which leads to the negative hydrophobic mismatch between the membrane and binding partners.

Can blood amyloid levels be used as a biomarker for Alzheimer’s disease?

Alzheimer’s disease (AD) increasingly affects society due to aging populations. Even at pre‐clinical stages, earlier and accurate diagnoses are essential for optimal AD management and improved clinical outcomes. Biomarkers such as beta‐amyloid (Aβ) or tau protein in cerebrospinal fluid (CSF) have been used as reliable markers to distinguish AD from non‐AD, and predicting clinical outcomes, to attain these goals. However, given CSF access methods’ invasiveness, these biomarkers are not used extensively in clinical settings. Blood Aβ has been proposed as an alternative biomarker since it is less invasive than CSF; however, sampling heterogeneity has limited its clinical applicability. In this review, we investigated blood Aβ as a biomarker in AD and explored how Aβ can be facilitated as a viable biomarker for successful AD management.

Sex and APOE genotype differences related to statin use in the aging population

Background

Significant evidence suggests that the cholesterol‐lowering statins can affect cognitive function and reduce the risk for Alzheimer's disease (AD) and dementia. These potential effects may be constrained by specific combinations of an individual's sex and apolipoprotein E (APOE) genotype.

Methods

Here we examine data from 252,327 UK Biobank participants, aged 55 or over, and compare the effects of statin use in males and females. We assessed difference in statin treatments taking a matched cohort approach, and identified key stratifiers using regression models and conditional inference trees. Using statistical modeling, we further evaluated the effect of statins on survival, cognitive decline over time, and on AD prevalence.

Results

We identified that in the selected population, males were older, had a higher level of education, better cognitive scores, higher incidence of cardiovascular and metabolic diseases, and a higher rate of statin use. We observed that males and those participants with an APOE ε4–positive genotype had higher probabilities of being treated with statins; while participants with an AD diagnosis had slightly lower probabilities. We found that use of statins was not significantly associated with overall higher rates of survival. However, when considering the interaction of statin use with sex, the results suggest higher survival rates in males treated with statins. Finally, examination of cognitive function indicates a potential beneficial effect of statins that is selective for APOE ε4–positive genotypes.

Discussion

Our evaluation of the aging population in a large cohort from the UK Biobank confirms sex and APOE genotype as fundamental risk stratifiers for AD and cognitive function, furthermore it extends them to the specific area of statin use, clarifying their specific interactions with treatments.

Causal AI with Real World Data: Do Statins Protect from Alzheimer's Disease Onset?

Causal artificial intelligence aims at developing bias-robust models that can be used to intervene on, rather than just be predictive, of risks or outcomes. However, learning interventional models from observational data, including electronic health records (EHR), is challenging due to inherent bias, e.g., protopathic, confounding, collider. When estimating the effects of treatment interventions, classical approaches like propensity score matching are often used, but they pose limitations with large feature sets, nonlinear/nonparallel treatment group assignments, and collider bias. In this work, we used data from a large EHR consortium -OneFlorida- and evaluated causal statistical/machine learning methods for determining the effect of statin treatment on the risk of Alzheimer's disease, a debated clinical research question. We introduced a combination of directed acyclic graph (DAG) learning and comparison with expert's design, with calculation of the generalized adjustment criterion (GAC), to find an optimal set of covariates for estimation of treatment effects -ameliorating collider bias. The DAG/CAC approach was assessed together with traditional propensity score matching, inverse probability weighting, virtual-twin/counterfactual random forests, and deep counterfactual networks. We showed large heterogeneity in effect estimates upon different model configurations. Our results did not exclude a protective effect of statins, where the DAG/GAC point estimate aligned with the maximum credibility estimate, although the 95% credibility interval included a null effect, warranting further studies and replication.

Statins for treatment of chronic liver disease

PURPOSE OF REVIEW

Statins are a class of lipid lower medications used primarily in patients with high-risk cardiovascular disease. Since their development, statins have been considered to be harmful in patients with liver disease, and many of the prescribing information labels consider them to be contraindicated in patients with active liver disease. However, recent studies have shown the contrary, warranting further investigation and discussion. This review aims to describe the latest literature on the mechanism, safety profile and potential benefits of statins use on the natural history of chronic liver disease (CLD) progression and its complications.

RECENT FINDINGS

A number of recently published studies have added to the existing body of literature supporting the concept that statins are safe and likely to be beneficial for treating patients with CLD. Patients with CLD including hepatitis B virus infection, hepatitis C virus infection, nonalcoholic fatty liver disease and alcohol on statins have been shown to have a lower rate of decompensating events, lower incidence of hepatocellular cancer, a lower rate of infections, and increased survival. However, the majority of the available literature supporting statin use in patients with liver disease comes from retrospective observational studies with high potential for bias.

SUMMARY

Statins appear to be safe in patients with compensated cirrhosis, and evidence suggests that they may reduce fibrosis, even in patients with advanced fibrosis and cirrhosis. Further high-quality research on this topic is needed to fully delineate the effect of statins in patients with liver disease.

Bridging Scales in Alzheimer's Disease: Biological Framework for Brain Simulation With The Virtual Brain

Despite the acceleration of knowledge and data accumulation in neuroscience over the last years, the highly prevalent neurodegenerative disease of AD remains a growing problem. Alzheimer's Disease (AD) is the most common cause of dementia and represents the most prevalent neurodegenerative disease. For AD, disease-modifying treatments are presently lacking, and the understanding of disease mechanisms continues to be incomplete. In the present review, we discuss candidate contributing factors leading to AD, and evaluate novel computational brain simulation methods to further disentangle their potential roles. We first present an overview of existing computational models for AD that aim to provide a mechanistic understanding of the disease. Next, we outline the potential to link molecular aspects of neurodegeneration in AD with large-scale brain network modeling using The Virtual Brain (www.thevirtualbrain.org), an open-source, multiscale, whole-brain simulation neuroinformatics platform. Finally, we discuss how this methodological approach may contribute to the understanding, improved diagnostics, and treatment optimization of AD.

Effect of statins on amyloidosis in the rodent models of Alzheimer's disease: Evidence from the preclinical meta-analysis

INTRODUCTION

Previous studies have shown contrasting results in determining efficacy of statins against amyloid beta accumulation. The aim of this study was to assess the impact of statin in AD.

METHOD

We searched PubMed and Embase for relevant preclinical studies. A meta-analysis of the statin's efficacy on amyloidosis and cognitive impairment was performed. Also, stratified analysis was performed on several covariates including the type of statin used, gender and age of rodents and duration of statin therapy, to account for the reported heterogeneity in the results obtained. The study protocol was registered in PROSPERO (CRD42018102557).

RESULT

17 studies including 22 comparisons, containing a sample size of 446 rodents, participated in the meta-analysis of statin's effect on overall Aβ deposition. Although the effect of statin on overall Aβ deposition was found to be protective (p < 0.00001) but as we categorized the efficacy of statin on different Aβ species (soluble and insoluble Aβ40/42) and Aβ plaque load, we found that significance in the protection decreased. A stratified meta-analysis demonstrated a significant role in the duration of statin supplements and rodent's age on the heterogeneity of the results. Statin administered to rodents for the longest duration (>6 months) and younger rodents (<6 months of age) demonstrated significant efficacy of statin on Aβ deposition.

CONCLUSION

Statin showed reduction in Aβ level but stratified analysis revealed that this effect of statin was dependent on rodent's age and duration of the treatment.

Can We Treat Neuroinflammation in Alzheimer's Disease?

Alzheimer's disease (AD), considered the most common type of dementia, is characterized by a progressive loss of memory, visuospatial, language and complex cognitive abilities. In addition, patients often show comorbid depression and aggressiveness. Aging is the major factor contributing to AD; however, the initial cause that triggers the disease is yet unknown. Scientific evidence demonstrates that AD, especially the late onset of AD, is not the result of a single event, but rather it appears because of a combination of risk elements with the lack of protective ones. A major risk factor underlying the disease is neuroinflammation, which can be activated by different situations, including chronic pathogenic infections, prolonged stress and metabolic syndrome. Consequently, many therapeutic strategies against AD have been designed to reduce neuro-inflammation, with very promising results improving cognitive function in preclinical models of the disease. The literature is massive; thus, in this review we will revise the translational evidence of these early strategies focusing in anti-diabetic and anti-inflammatory molecules and discuss their therapeutic application in humans. Furthermore, we review the preclinical and clinical data of nutraceutical application against AD symptoms. Finally, we introduce new players underlying neuroinflammation in AD: the activity of the endocannabinoid system and the intestinal microbiota as neuroprotectors. This review highlights the importance of a broad multimodal approach to treat successfully the neuroinflammation underlying AD.

Repositioning medication for cardiovascular and cerebrovascular disease to delay the onset and prevent progression of Alzheimer's disease

Alzheimer's disease (AD) is a complex, progressive, neurodegenerative disorder. As with other common chronic diseases, multiple risk factors contribute to the onset and progression of AD. Many researchers have evaluated the epidemiologic and pathophysiological association between AD, cardiovascular diseases (CVDs), and cerebrovascular diseases (CBVDs), including commonly reported risk factors such as diabetes, hypertension, and dyslipidemia. Relevant therapies of CVDs/CBVDs for the attenuation of AD have also been empirically investigated. Considering the challenges of new drug development, in terms of cost and time, multifactorial approaches such as therapeutic repositioning of CVD/CBVD medication should be explored to delay the onset and progression of AD. Thus, in this review, we discuss our current understanding of the association between cardiovascular risk factors and AD, as revealed by clinical and non-clinical studies, as well as the therapeutic implications of CVD/CBVD medication that may attenuate AD. Furthermore, we discuss future directions by evaluating ongoing trials in the field.

Protocol for systematic review and meta-analysis: impact of statins as immune-modulatory agents on inflammatory markers in adults with chronic diseases

INTRODUCTION

Statins, also known as 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) reductase inhibitors, are lipid-lowering agents that are central in preventing or reducing the complications of atherosclerotic cardiovascular disease. Because statins have anti-inflammatory properties, there is considerable interest in their therapeutic potential in other chronic inflammatory conditions. We aim to identify the statin with the greatest ability to reduce systemic inflammation, independent of the underlying disease entity.

METHODS AND ANALYSIS

We aim to conduct a comprehensive search of published and peer-reviewed randomised controlled clinical trials, with at least one intervention arm of a Food & Drug Administration-licensed or European Medicines Agency-licensed statin and a minimum treatment duration of 12 weeks. Our objective is to investigate the effect of statins (atorvastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin) on lipid profile, particularly, cholesterol low-density lipoprotein and inflammation markers such as high-sensitive C reactive protein (hsCRP), CRP, tumour necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), IL-6, IL-8, soluble cluster of differentiation 14 (sCD14) or sCD16 in adults, published in the last 20 years (between January 1999 and December 2019). We aim to identify the most potent statin to reduce systemic inflammation and optimal dosing. The following databases will be searched: Medline, Scopus, Web of Science and Cochrane Library of Systematic Reviews. The risk of bias of included studies will be assessed by Cochrane Risk of Bias Tool and Quality Assessment Tool for Quantitative Studies. The quality of studies will be assessed, to show uncertainty, by the Jadad Score. If sufficient evidence is identified, a meta-analysis will be conducted with risk ratios or ORs with 95% CIs in addition to mean differences.

ETHICS AND DISSEMINATION

Ethics approval is not required as no primary data will be collected. Results will be presented at conferences and published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42020169919.

The contribution of vascular risk factors in neurodegenerative disorders: from mild cognitive impairment to Alzheimer's disease

Background

Optimization of vascular risk factor control is emerging as an alternative approach to improve cognitive outcomes in Alzheimer’s disease, although its efficacy is still under debate. We aimed to investigate the contribution of vascular risk factors on Alzheimer’s biomarkers and conversion rate to dementia in subjects with mild cognitive impairment (MCI) with low cerebral small vessel disease burden.

Methods

Two hundred ninety-five newly diagnosed MCI subjects were enrolled from March 2005 to May 2017 for a cross-sectional assessment of vascular risk factors and Alzheimer’s plasma and imaging biomarkers, followed by a cognitive outcome assessment 24 months after enrollment. The association between vascular risk factors and Alzheimer’s biomarkers were tested using multivariable linear regression models adjusted with age, gender, education, and APOE ε4 allele. The association between vascular risk factors and conversion to dementia was tested using multivariable logistic regression models adjusted with age, gender, education, and baseline Mini-Mental State Examination (MMSE) score.

Results

At baseline, higher low-density lipoprotein (LDL) cholesterol level was associated with more advanced plasma biomarkers, including Aβ42/Aβ40 ratio (P = 0.012) and tau level (P = 0.001). A history of hypertension was associated with more advanced white matter hyperintensity (P = 0.011), while statin therapy for dyslipidemia was associated with less advanced white matter hyperintensity (P = 0.002). At 24 months, individual vascular risk factor was not significantly associated with cognitive outcome. By contrast, statin therapy for dyslipidemia was associated with reduced conversion to dementia (adjusted OR = 0.191, 95% CI = 0.062~0.586, P = 0.004).

Conclusions

For MCI subjects, dyslipidemia may contribute to AD-related neurodegeneration while hypertension may contribute to vascular pathology. The association between statin therapy for dyslipidemia and reduced conversion to dementia supports further interventional study to evaluate the potential beneficial effect of statin in MCI subjects.

MAM and C99, key players in the pathogenesis of Alzheimer's disease

Inter-organelle communication is a rapidly-expanding field that has transformed our understanding of cell biology and pathology. Organelle-organelle contact sites can generate transient functional domains that act as enzymatic hubs involved in the regulation of cellular metabolism and intracellular signaling. One of these hubs is located in areas of the endoplasmic reticulum (ER) connected to mitochondria, called mitochondria-associated ER membranes (MAM). These MAM are transient lipid rafts intimately involved in cholesterol and phospholipid metabolism, calcium homeostasis, and mitochondrial function and dynamics. In addition, γ-secretase-mediated proteolysis of the amyloid precursor protein 99-aa C-terminal fragment (C99) to form amyloid β also occurs at the MAM. Our most recent data indicates that in Alzheimer's disease, increases in uncleaved C99 levels at the MAM provoke the upregulation of MAM-resident functions, resulting in the loss of lipid homeostasis, and mitochondrial dysfunction. Here, we discuss the relevance of these findings in the field, and the contribution of C99 and MAM dysfunction to Alzheimer's disease neuropathology.

Selected LDLR and APOE Polymorphisms Affect Cognitive and Functional Response to Lipophilic Statins in Alzheimer's Disease

Effects of statins over clinical changes in Alzheimer's disease (AD) are usually non-significant, but epistatic interactions between genetic variants involved in cholesterol metabolism could be important for such effects. We aimed to investigate whether LDLR single-nucleotide polymorphisms rs11669576 (LDLR8), rs5930 (LDLR10), and rs5925 (LDLR13) are associated with cognitive and functional changes in AD, while also considering APOE haplotypes and lipid-lowering treatment with lipophilic statins for stratification. Consecutive outpatients with late-onset AD were screened with cognitive tests, while caregivers scored functionality and caregiver burden, with prospective neurotranslational correlations documented for 1 year. For 179 patients, minor allele frequencies were 0.078 for rs11669576-A (14.5% heterozygotes), 0.346 for rs5930-A (42.5% heterozygotes), and 0.444 for rs5925-C (56.4% heterozygotes), all in Hardy-Weinberg equilibrium; 134 patients had hypercholesterolemia, and 133 used lipophilic statins. Carriers of rs11669576-G had faster cognitive decline, while functional decline was slower for carriers of rs11669576-A who used lipophilic statins. APOE-ε4 carriers who also carried rs5930-AA had improved caregiver burden, while carriers of haplotypes that included rs5930-AG had worse cognitive and functional outcomes, though carriers of the A allele of rs5930 had better cognitive and functional response to lipophilic statins. APOE-ε4 non-carriers who carried rs5925-TT had slower cognitive decline, while lipophilic statins protected carriers of the other genotypes. We preliminarily conclude that reportedly protective variants of LDLR and APOE against risk of AD also slowed cognitive decline, regardless of cholesterol variations, while therapy with lipophilic statins might benefit carriers of specific genetic variants.

Is Alzheimer's Disease Risk Modifiable?

Population-based clinic-pathological studies have established that the most common pathological substrate of dementia in community-dwelling elderly people is mixed, especially Alzheimer's disease (AD) and cerebrovascular ischemic disease (CVID), rather than pure AD. While these could be just two frequent unrelated comorbidities in the elderly, epidemiological research has reinforced the idea that mid-life (age <65 years) vascular risk factors increase the risk of late-onset (age ≥ 65 years) dementia, and specifically AD. By contrast, healthy lifestyle choices such as leisure activities, physical exercise, and Mediterranean diet are considered protective against AD. Remarkably, several large population-based longitudinal epidemiological studies have recently indicated that the incidence and prevalence of dementia might be decreasing in Western countries. Although it remains unclear whether these positive trends are attributable to neuropathologically definite AD versus CVID, based on these epidemiological data it has been estimated that a sizable proportion of AD cases could be preventable. In this review, we discuss the current evidence about modifiable risk factors for AD derived from epidemiological, preclinical, and interventional studies, and analyze the opportunities for therapeutic and preventative interventions.

Effects of saffron (Crocus sativus L.) on cognitive function. A systematic review of RCTs

INTRODUCTION

Improvement of cognitive function may be desirable for healthy individuals and clinically beneficial for those with cognitive impairment such as from Alzheimer's disease (AD) or mild cognitive impairment (MCI). The aim of this systematic review is to investigate the cognitive effects of oral saffron intake, in patients with MCI/AD and/or in non-demented individuals, by following the PRISMA guidelines.

METHODS

We performed a literature search on MedLine, Cochrane library, and ClinicalTrials.gov to identify randomized controlled trials (RCTs) investigating the effects of oral saffron administration in patients with MCI/AD and/or in non-demented individuals.

RESULTS

Five studies (enrolling 325 individuals) met our inclusion criteria. Four studies included patients with MCI/AD, and one study included cognitively normal individuals. Saffron was well-tolerated in all groups. Regarding cognitively impaired patients, scores on Alzheimer's Disease Assessment Scale-cognitive subscale or Mini mental state examination were significantly better when saffron was compared with placebo and did not differ significantly when saffron was compared with donepezil or memantine. Saffron effects on functional status were similar with its effects on cognition.

CONCLUSIONS

Saffron was shown to be equally effective to common symptomatic drugs for MCI/AD and resulted in no difference in the incidence of side effects, when compared with placebo or drugs. The promising results should be seen cautiously, since the evidence was derived from studies with potentially high risk of bias (ROB). RCTs with larger sample sizes and low ROB are required to definitively assess the potential role of saffron as an MCI/AD treatment.